1. Field of the Invention
The present invention relates to a waterproof sound transmitting member suitable for providing waterproof function to electronic devices equipped with acoustic components such as microphones and speakers, and in particular, to a waterproof sound transmitting member including a waterproof sound transmitting membrane.
2. Description of Related Art
Portable electronic devices, such as cellular phones, cordless phones, smartphones, notebook computers, tablet computers, electronic notebooks, digital cameras, and portable game machines, are required to be waterproof because the devices are often used outdoors. In these electronic devices, acoustic components, specifically, transducers serving as sound transmitters or sound receivers, such as speakers, microphones, and buzzers, need to transmit sound to the outside of the devices and to receive sound from the outside thereof. Therefore, various studies have been conducted to achieve both sound transmission and waterproofness.
One of the known ways to provide both waterproofness and sound transmission (waterproof sound transmission function) to an electronic device is to attach a waterproof sound transmitting membrane to a housing of the electronic device to cover an opening formed in the housing. Nonwoven fabrics or porous polymer membranes and films are used as waterproof sound transmitting membranes. Waterproof sound transmitting members each including a waterproof sound transmitting membrane and a fixing member for fixing the waterproof sound transmitting membrane are disclosed in JP 2001-148897 A, JP 2004-083811 A, and JP 2012-165353 A, for example. JP 2012-165353 A discloses a waterproof sound transmitting member including a waterproof sound transmitting membrane in which two sheets having different stiffnesses are laminated together to reduce chattering noise.